Please check the HTTP API document:
https://openthings.freshdesk.com/support/solutions/articles/5000716363-os-api-documents
page 5, section 12, “Manual Station Run” /cm. The ‘ssta’ parameter can be used to skip a current running or scheduled station.
Per the support article for MQTT:
https://openthings.freshdesk.com/support/solutions/articles/5000859089-how-to-use-mqtt
the /cm command is also supported by MQTT.